In recent years, safety monitoring technology has become an important technology for the industries and government units to monitor, in particular, buildings or facilities with high technology, military or administrative secret. However, the physical monitoring system has its physical limitations and may lead to detection losses (e.g., a failure to detect an intruder that does exist) or false alarms (e.g., a wrong detection of an intruder that does not exist) because the detection result of the physical monitoring system has been affected by factors such as environmental factor (including weather situation) and so on.
In general, the damage resulting from the detection losses may be greater than that of the false alarms. Hence, a conventional approach is to increase the sensitivity of the physical monitoring system so as to avoid the detection losses. However, such approach may cause the monitoring personnel to receive alarm messages of false alarms frequently, and the monitoring personnel may thus insensitive to the alarm messages and ignore the alarm messages of correct alarms. In addition, replacing the current physical monitoring system with a more accurate physical monitoring system can resolve the above technical problem; however, the replacement may increase the cost additionally.